class Circle:
   _pi = 3.14

   def __init__(self, radius):
       self._radius = radius

   @property
   def radius(self):
       return self._radius

   @property
   def pi(self):
       return self._pi

   def calculate_area(self):
       return self._pi * self._radius ** 2


class SemiCircle(Circle):
   def calculate_area(self):
       return super().calculate_area() / 2
  
code = []
while data := input():
   code.append(data)
code = "\n".join(code)
exec(code)